Electric incandescent lamp.



A. E. APPLEYARD.

ELECTRIC INCANDESCENT LAMP.

APPLICATION FILED FEB. 13. I914.

1,156,967. Patented Oct. 19, 1915.

Z'W EWNZMWW@ TED SATS ATE OFF ELECTRIC INCANDESCENT LAMP.

Specification of Letters Patent.

Application filed February 13, 1914.. Serial No. 818,474.

To all whom it may concern:

Be it known that I, Alrrimn E. APPLE- rAnn, a citizen of the United States, and resident of Ashland, in the county of Ash land and State of Wisconsin, have invented certain new and useful Improvements in Electric Incandescent Lamps, of which the following is a specification.

This invention relates to electric incandescent lamps, and its object is to provide the lamp with a filament of special form, such as an alphabetic, numeric or other character.

The invention seeks to overcome certain objections incidental to the structure shown in U. S. Letters Patent to Hawkins, 573,088, granted December 15, 1896. In that patent the vacuum chamber in which the filament is arranged is built up of a plurality of parts which require joints. It is practically impossible to form a joint which will maintain the desired vacuum for the necessary length of time, and for this reason the builtup vacuum chamber of Hawklns is not adapted to give the desired result. I have overcome this difficulty by using a seamless glass bulb and leading-in wires like those now in general use.

Carbon filaments can be produced only by giving them the desired form before they are baked, and it is difficult to preserve a perfect form during baking. At the time of filing the application which resulted in the 'said patent to ll awkins, carbon filaments were the only filaments which had been perfected sufliciently for general use. Since then, however, tungsten wire has been discovered and is extensively used. Tungsten wire can be given any desired shape, provided the wire is heated while being shaped, and I avail myself of this advantage in shaping the filament for my present device.

The length of filament required for alphabetic characters of uniform size varies, and for this reason it would be difficult or impossible to form different characters from carbon filaments of the same length. For electrical reasons it is necessary to have the filaments of the same cross-sectional area and length, in order to have uniform luminosity; and for this reason filaments of tungsten wire are better adapted to be used for forming different characters because they are about twice as long as carbon filaments of the some current. rating, and are sullicicnt for characters such as W which require more length than some others such as I and 0. By using tungsten wire I am enabled to form the outlines of a letter in duplicate-or triplicate and to connect the outlines in series with each other and arrange one behind the other so that when the device is viewed from the front it will appear as a single character, whereas it may, in fact, have a plurality of characters one behind the other. A furtheradvantage of using a relatively long filament is that each character may be given a double outline to produce the effect of greater bulk, as may be understood by referring to the drawings.

()f the accompanying drawings, which Illustrate in what manner my invention may be embodied: Figure '1 represents an end elevation of an incandescent lamp bulb in which the filament is arranged to form an alphabetic character whose plane is transverse to the axis of the bulb. Fig. 2 represents a side elevation of the bulb in which thefilament is arranged as shown by Fig. 1. Fig. 3 is a diagram representing the electric circuit accordingto Figs. 1 and 2, the filament being divided into three sections each of which forms a double outline of the alphabetic character. The several sections of the filament are connected in series with each other and are arranged one behind the other so as to give the appearance of but a Patented Oct. 19,1915. 1

single character when viewed according to grees distant from that of Fig. 4. with refer- I once to the axis of the bulb; In Fig. 5 the filament is divided into two. sections which are connected in series and disposed one behind the other.

The same reference characters indicate the same parts wherever they occur.

A seamless glass bulb of standard type is indicated at 10, the same being provided with a screw-plug 11 for attaching the bulb to a socket (not shown).- In the form shown by Figs. 1, 2 and 3, the filament comprises three sections, indicated at 12, 13 and 1-1 respectively, and connected in series with each other by conductors 15 of relatively low resistance. The leading-in Wires are indicated at 16 and 17 respectively, the sevthe letter E-and the said sections are arranged one behind the other so that there will appear to be but one character when the same is viewed from the front, as shown by Fig. 1; the filament sections, according to this arrangement, being intended to be viewed in a line parallel to the axis of the bulb. The filament is made of material of relatively low resistance, such as tungsten wire, as distinguished from high-resistance carbon filament. Experience has shown that for a circuit of 1.10 to 120'volts the total length of tungsten filament should be eighteen inches. As the character E of the size illustrated requires only six inches of filament, I provide the necessary surface by providing three characters whose total length of filament is eighteen inches. The

number of characters is not wholly optional, but is determined by the total length of eighteen inches required; and consequently, if a single character should require nine inches of filament, I would provide only two characters, in order to make up the total of eighteen inches, whereas if each character required only three inches I would provlde six such characters to make up the total of eighteen inches, and would arrange them as shown, one behind another, so that there would appear to be but one character when the device is viewed from the front of. the

foremost character.

It will be observed that each character has a double outline; that is to say, the thickness of the character is not limited to a single thickness of filament but includes the space between adjacent parallel stretches of filament. This arrangement of the filament gives the character the appearance of considerable body and renders the character more legible and more pleasing in appearance than one whose thickness of body is limited to a single thickness of filament. The terminals of each section or character are adjacent to each other, the slight gap between them being so limited that it does not perceptibly break the continuity of the visual effect. In order to identify the incandescent filament members I have represented the same by relatively heavy lines and the filament supports and non-incandescent conductors by relatively light: lines in all the figures.

Each filament section is supported at a plurality of points by supporting members 18. These members may be made of wire, provided they are insulated from each other. As shown by Fig. 2, the members 18 are mounted upon a central post 19 of non-conducting material, such as glass, this post beingafiixed to a base 20 of non-conducting material, which in the present instance is a is given for relieving the vacuum in the bulb.

This reentrant integral formation has been found to be necessary because no one, up to the present'time, has been able to form a joint which will hold the vacuum for a sufficient period of time to render the same commercially possible.

I provide the leading in wires 16 and 17 with short platinum sections 21 where they pass through the base 20, this being standard practice in order to avoid leakage at those points, as the expanding and contracting action of platinum is substantially the same as that of glass. The supporting members 18 are preferably arranged at the angles of the characters, thus not only performing their primary function of supporting the filament sections but also acting to hold the sections in the desired shape.

In the modification shown by Figs. 4: and 5, the same alphabetic character E is shown but is arranged to stand in a plane parallel to the axis of the bulb, this arrangement permitting a larger character to be inclosed in a bulb of the same size. In this embodiment each single character requires nine inches of filament, and for this reason but two characters are necessary to make up the required total of 18 inches. The two sections of the filament are shown arranged one behind the otherin Fig. 5 and are indicated respectively at 22 and 23. The supporting members therefor are indicated at 18, and the post of insulating material is indicated at 19, the arrangement of these elements being substantially the same as in the form first described, excepting where slight changes are necessitated by the difierent position of the luminous character and by its size.

Another advantage of dividing the filament into sections is that a greater volume of light is radiated edgewise from the characters, the efiiciency of the filaments for unrestricted illumination being greater than if the entire filament were in one section and all portions thereof arranged in a single plane.

The showing of the supports 18 is somewhat conventional, and for thisreason there is inconsistency'between the difierent views of the same device. This conventional show ing is preferred for the sake of avoiding confusion which would result if all the supporting members were shown according to their actual arrangement in practice. Fig. 1, for example, I have shown the supporting members for but one section of the filament, and in Fig. 2 I have shown only two supporting members for each section of the filament and have arranged them so that each is set apart from the others. It will be understood, therefore, that the showing of the supports is intended to illustrate how they serve their purpose rather than to illustrate their actual arrangement.

My invention may be embodied in incandescent lamps filled with nitrogen or other gases under pressure as, well as in lamps of the vacuum type.

I claim 1. An electric incandescent lamp comprising a plurality of separate filament members of like form, each of which defines the outline of a sign character, said members being arranged one behind another, and nonincandescent conductors connecting said members in series.

2. An electric incandescent lamp comprising a plurality of separate filament members of like form such as an alphabetic or numeric character, said members being arranged one behind another, non-conducting supports sustaining said members independently of each other, and non-incandescent conductors connecting said members in senos.

3. An electric incandescent lamp comprising a filament member the ends of which are adjacent each other, said member being formed to define the outline of a sign character of greater thickness than said member.

In testimony whereof I have affixed my signature, in presence of two witnesses.

ARTHUR E. APPLEYARD.

Witnesses:

E. J. SHAYLOR, ELEANOR M. Gns'rArsoN. 

